This invention relates to the determination of geometrical dimensions and physical characteristics of objects as well as viewing and measurement of their limited access areas. More particularly, this invention relates to the inspection and measurement of surfaces without disassembling or otherwise altering the piece parts or other article. Important aspects of the present invention are machine tools comprising the necessary features for viewing and measuring desired portions of an object while it is being mounted within the particular machine tool.
It has been possible for some period of time to examine the interior of items. U.S. Pat. No. 1,775,452 describes an instrument for examining the interior of gun barrels and tubes. In particular borescopes have been long established as instruments for the inspection of bore surfaces in elongate articles. Normally the viewer looks through an eye piece to view the interior of the object. Some borescopes are constructed so as to permit the taking of photographs through the eyepiece. Also the Lenox Instrument Company has proposed a system consisting of a color video minicamera module, a color monitor, a camera adapter for attaching the camera to the eyepiece of a borescope and a borescope. This borescope system does not include equipment or methods for the measurement of the interior surface of an object.
U.S. Pat. No. 4,078,864 also shows the use of a camera to deliver a picture to display a generally inaccessible area. In addition this patent discloses the use of a camera for taking a picture of an object having damage. This patent's main thrust is to a method for measuring a generally inaccessible dimension of an object viewed through an optical viewing tube. It utilizes a method comprising placing a glass reticle having a previously marked unit of length for the focussed distance over a photograph of the object.